Improve typing and sidebar performance in large workspaces

packages/common-lib/debounce.ts

@@ -1,13 +1,32 @@
 // oxlint-disable-next-line no-explicit-any
 export function debounce(fn: (...args: any[]) => void, delay = 500) {
-  let timer: ReturnType<typeof setTimeout>;
+  let timer: ReturnType<typeof setTimeout> | null = null;
+  // oxlint-disable-next-line no-explicit-any
+  let lastArgs: any[] | null = null;
   // oxlint-disable-next-line no-explicit-any
   const result = (...args: any[]) => {
-    clearTimeout(timer);
-    timer = setTimeout(() => fn(...args), delay);
+    lastArgs = args;
+    if (timer != null) clearTimeout(timer);
+    timer = setTimeout(() => {
+      timer = null;
+      const argsToUse = lastArgs ?? [];
+      lastArgs = null;
+      fn(...argsToUse);
+    }, delay);
   };
   result.cancel = () => {
+    if (timer != null) clearTimeout(timer);
+    timer = null;
+    lastArgs = null;
+  };
+  // Invoke a pending call immediately instead of waiting out the delay
+  result.flush = () => {
+    if (timer == null) return;
     clearTimeout(timer);
+    timer = null;
+    const argsToUse = lastArgs ?? [];
+    lastArgs = null;
+    fn(...argsToUse);
   };
   return result;
 }